Dry air cleaner



Dec. 19, 1961 w. w. LOWTHER 3,013,629

DRY AIR CLEANER Filed Oct. 27, 1959 IN V EN TOR.

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United States Patent 3,013,629 DRY AIR CLEANER Wilfred W. Lowther, Chicago, Ill., assignor to Novo Industrial Corporation, a corporation of New York Filed Oct. 27, 1959, Ser. No. 849,057 9 Claims. (Cl. 183-34) This is a continuation-in-part of Serial No. 693,372, filed October 30, 1957, now abandoned.

My invention is in the field of air cleaners for cleaning air intended to be used with air consuming devices, such as internal combustion engines of all types, air compressors and the like.

A primary object of my invention is a device for cleaning air which sets up a rotating or swirling cylinder or annulus so that dirty air may be separated at the outside of the cylinder from clean air on the inside.

Another object is an air cleaning device that will sup ply the same quantity of air as a conventional cleaner but is a much smaller unit.

Another object is an air cleaning device that does not use any washing liquids or fluids.

Another object is an air cleaning device that will provide a mild supercharge when the device is used with an engine or other prime mover.

Another object is an air cleaner that provides little if any restriction.

Another object is an air cleaner with an insertable cartridge which may be easily removed and cleaned.

Another object is an air cleaner which may be powered by an outside source or may have its own power source.

Another object is a highly eflicient air cleaner which is inexpensive to manufacture.

Another object is an air cleaner which is small in size and accordingly requires little head room, for example, in automotive use.

Another object is an air cleaner that will function efficiently in any position, right side up, upside down or otherwise.

Another object is a multi-stage air cleaner.

Other objects will appear from time to time in the ensuing specification and drawings in which:

FIGURE 1 is a side view, half in axial section, showing my air cleaner; and

FIGURE 2 is an end view of FIGURE 1, taken along line 2-2.

In FIGURE 1, the cleaner includes an outer housing 10 which may be and is shown as generally cylindrical. What I shall refer to as the forward end of the housing has a bullet nose or shroud 14 which may be connected to the housing at 16 in any suitable manner, such as by welding.

An inner bafiie or sleeve 18, which may also be cylindrical or shaped to conform, more or less, to the outer housing, is suitably mounted in the outer housing by a plurality of braces or connections 20, preferably three. The sleeve is spaced from the housing and provides an open annular channel or passage 22 and is shaped inwardly in its forward region, as at 24, to provide a fan chamber 26 in the forward part of the over-all unit.

A fan 28, preferably a centrifugal type fan rotor, such as shown generally in United States Patent No. 2,272,695, not a positive displacement unit, including an end plate 30, is mounted on a suitable drive shaft 32 through a hub 34 or the like. A plurality of blades 36 are connected to the outer end of the end plate 30, by crimping or otherwise, and joined at the other end by a suitable ring 38 or the like. The forward portion or one side of such a rotor is open, as at 40, which functions as an inlet and the air drawn into the interior of the rotor is thrown outwardly by the blades in a centrifugal action.

The forward edge of the shroud 14 is curved or otherwise formed, as at 42, around the forward edge of the fan rotor to provide a central inlet for air to be cleaned and also to shield or mask the forward edge or ring 38 of the fan rotor against recirculation of air.

The shaft 32 may be held at one end by a suitable bearing 44 or otherwise mounted for rotation in a socket or seat 46 which may be formed in a cap 48 in the inner shield. The forward portion of the shaft may be carried by a'suitable bearing 50 mounted on an end cap 52 or the like which may be welded or otherwise suitably connected across the open front end of the housing. The cap 52 is provided with a plurality of openings 54 which in total area exceed the area of the inlet in the shroud 14 so that air may freely flow into the fan rotor. The drive shaft may project forward through the cap and carry a pul ey 56 or the like to be driven by a suitable belt or otherwise.

An important point to note is that the shroud or nose 14 increases in cross sectional area from'its forward curved portion 42 to the point generally opposite the end of the fan chamber. This may be thought of as the shroud for the fan developing in an axial direction and leading smoothly into the open annular passage 22 between the inner sleeve 18 and the housing.

An end cap or wall 58 closes the rear end of the housing and has a centrally disposed outlet 60 projecting through it. The end cap has a lateral annular surface 62, an inwardly diverging portion 64, a lateral surface 66 with a slight rearward flare and a rearward cylindrical edge 68. Portions of the rear edge may be offset, as at 70, to provide spaced projections or buttons which engage the inside of the housing. A filter element, designated generally 72, is disposed in the housing and projects forward from the rear cap or wall 58. As shown, the filter element is generally cylindrical and annular with its inner surface defined by an expanded wire or metal mesh 74 and a corresponding outer shell or sleeve of expanded metal or mesh, at 76, connected at their rear edges by an annular channel or cap 78. The filter has a forward cap or closure and an inner ring 82, both being indented or offset, at 84, to conform and telescope over the socket 46.

The outlet 60 has an outwardly turned flange which is welded or otherwise tightly connected to the rear end of the filter element and is removable with it. It will thus be seen that the outlet 60 projects through the end cap 58 and the filter element and outlet are supported on the inwardly diverging portion 64 of the end cap, but a seal between the end cap and the end of the filter ele ment is not necessary. Nor is a seal required between the front of the element and the sleeve or baffle 18. In fact, seals are completely eliminated.

The outside of the housing may be provided with one or more suitable mounting brackets 86 and the rear end of the housing may be surrounded by a suitable band or strap 88, if desired, with latches 89 to releasably hold the filter element in the housing. The lower latch in FIGURE 2 has not been shown in FIGURE 1, for clarity.

An important point is that the annular air passage 22 is completely open up to and including the areas lat- ,erally bounding the fan. Note that the shroud 14 conforms to and is closely spaced to the front edge of the fan and then develops or increases rearwardly so that the space between the fan and the housing, as defined 'by the shroud 14, increases rearwardly and is totally open.

of the dirt can move in the opposite direction or in any way become isolated or separated from the helical swirl.

The use, operation and function of the invention are as follows:

Any suitable driving means rotates the centrifugal rotor through the pulley 56. Air is drawn through the front end of the housing by the fan and expelled outwardly against the axially developing shroud and formed into an annular column of helically swirling air moving rearwardly through passage 22. Due to the rotation of the rotor, the air moving through passage 22 has a swirling or rotary motion. This motion centrifuges and throws the air against the housing and the heavier particles of dirt tend to slide along the inside surface of the housing. In effect, I have created a swirling column of air which, due to its swirling or centrifugal motion, throws the heavy dirt particles to the outside. The fan creates an excess of air and I discharge this excess with the dirt through the annular ring of slots 71 at the rear end of the housing. The cleaner air remains on the inside of the cylinder or column and is drawn through the filter element 72 and discharged through the outlet 60 to the air consuming device, be it an engine or otherwise.

In a sense, the centrifuging action precleans the air before it gets to the filter element. This is to say that centrifugal force precleans the air and discharges the vast majority of the dirt and dust through the annular slots 71. Thus, the filter element itself has much less dirt and dust to contend with.

In actual tests on a unit of this type, I have found that on the order of 94 or 95 percent of the dirt will be discharged through the slots 71 and the rest, except for a microscopic amount, will be removed in the filter element 72.

It is also important to note that the filter element extends up inside of the shield or baifie 18. But since the battle is flared outwardly somewhat, air may recirculate back up inside of the baffle in the region designated 1 4) so that the full length of the filter element is usable. After an extended period of use, if the portion of the filter element between the rear edge of the shield or baffle 18 and the rear end of the housing begins to fill up with dirt, air may fiow back up in area 90 and the forward part of the filter element, designated 92, will be fully usable.

One advantage of this arrangement is its compactness. It will be noted that from the inlet of the shroud 14 to the rear end of the housing, the fan and filter element occupy practically the entire axial distance. The nose cap which provides a forward bearing support for the fan drive is optional. driven in any suitable manner. For example, a small electric motor might be mounted inside of the housing, for example, at the area designated more or less 84, although it would be substantially larger. Or an outside source of power, such as through the pulley 56, may be used.

When the restriction through the cleaner rises to a point indicating that the filter element needs cleaning, the brackets or clamps 89 may be loosened after the clean air connection is broken and the filter element 72 and end plate 58 removed. After cleaning, the filter element may be reinserted and it will be noted that the sleeve 18 functions to pilot or guide the forward end of the filter element of its proper concentric position in the housing. Additionally, the socket 46 fits in the offset 84- in the forward caps on the filter element to stabilize the unit when it is fully inserted.

The fan rotor, in a sense, provides an excess of air which is used to discharge dirt through the openings 71. There will be a positive fiow of air out through these openin gs and in addition the dirt will have suflicient momentum to discharge itself.

The spinning or rotary motion is important since it is the centrifugal action that throws the dirt against the inside of the housing. I might position Skimmers along As a matter of fact, the unit may be A the surface of the housing in addition to the outlets, but at the moment I find it convenient to merely discharge the dirty excess air through an annular ring of outlets in the end wall. I find it desirable to form the forward edge of the shroud around the forward edge of the rotor so that a recirculation or eddy current of air will not be set up. This additionally conveys the dirty air from the outside through the forward opening within the confines of the rotor. The blades of the rotor throw the dirty air outwardly against the shroud which increases in cross section toward the rear. The centrifugal fan rotor, in addition to throwing the heavy dirt particles against the side of the housing, also sets up a rotary or swirling motion which augments the centrifuging action.

While the centrifugal fan unit, as shown, is not intended to be a positive displacement unit and, therefore, will not create but a small amount of pressure in the annular passage leading to the after cleaner, nevertheless, a mild positive pressure above atmospheric will be created. Since the restriction or pressure differential across the filter cartridge will be the same, the pressure on the inside will be greater than otherwise. In addition to providing an excess of air for cleaning purposes, the fan rotor also provides a mild supercharge, which either substantially or completely eliminates any restriction caused by the filter cartridge. The cleaner has the additional advantage that there is no liquid involved and, accordingly, a pull-over problem is not present.

I have also found that the fan rotor tends to break up the disturbing sound waves that originate in the engine and are emitted by the inlet pipe and, in a sense, the device will automatically function as a silencer.

I might also add that the unit has particular advantage in the rain, meaning that heavy water or moisture particles will be thrown to the outside by the centrifugal action of the fan and discharged through the ring of outlet slots along with the dirty air.

While I have shown the annular dirt discharge passage as open, it should be understood that the dirt might be discharged to a closed jar or dead air space. This would be particularly advantageous where it is desired to collect and save the foreign matter in the air where it is something other than dirt, for example, certain chemicals in a processing plant.

While I have shown and described the preferred form and suggested various modifications of my invention, it should be understood that numerous additional modifications, changes, substitutions and alterations may be made without departing from the inventions fundamental theme. I, therefore, wish that my invention be unrestricted except as by the appended claims.

I claim:

1. In an air cleaner, a generally cylindrical housing open front and rear, a rear wall closing the rear of the housing, a rotatably mounted centrifugal fan rotor in the front of the housing and means for rotating it, the housing having a forward shroud extending forward across the fan rotor and inward around the front of the fan rotor, a centrally disposed inlet in the shroud opening inside the fan rotor, the shroud increasing uniformly in cross section rearwardly from the centrally disposed inlet to a point generally opposite the rear of the fan rotor, an inner somewhat cylindrical bafile directly next to the rear of the fan rotor extending rearwardly therefrom and terminating in spaced relation to the rear wall, the bafile being spaced from and defining with the housing a rearwardly extending open annular air passage having an inside diameter generally the same as the periphery of the fan rotor, the rear wall having a centrally disposed rear outlet for clean air with an outside diameter less than the diameter of the bafile, outlet means of generally annular form for dirty air in the rear wall around the clean air outlet having an outer diameter substantially that of the outer diameter of the annular air passage, and a cylindrical filter element extending at least from the rear edge of the inner bafile to the rear wall between the dirty and clean air outlets.

2. The structure of claim 1 further characterized by a cap mounted on the front of the housing and extending forwardly from the forward shroud, the fan rotor having a shaft extending forwardly through the cap, openings through the cap to allow for the entrance of air to be cleaned, and a drive pulley on the forward end of the drive shaft for driving the fan rotor.

3. The structure of claim 1 further characterized in that the rear wall is in the form of an end cap removably connected to the rear of the housing and having a central opening accepting the outlet of the filter element, the outlet being a part of the filter element and projecting through the central opening in the end cap and extending beyond the peripheral confines of the housing.

4. The structure of claim 1 further characterized in that the rear wall is in the form of an end cap removably connected to the rear of the housing and having a central opening accepting the outlet of the filter element, the out let being a part of the filter element and projecting through the central opening in the end cap and extending beyond the peripheral confines of the housing, the filter element and outlet being removably mounted in the housing and removed separately from the end cap.

5. The structure of claim 1 further characterized in that the inner baffie is slightly frusto-conical and is smaller at the front end than at the rear and is spaced at all points from the inside of the housing.

6. The structure of claim 1 further characterized in that the filter element extends forward inside of the inner baffle to a point adjacent to the fan rotor, the inside of the inner bafile being spaced outwardly and out of contact with the outside of the filter element so that air may pass around the rear edge of the bafile and through the forward portion of the filter element within the confines of the battle.

7. The structure of claim 1 further characterized in that the front end of the filter element is closed by a cap, and further including a centrally located depression in the cap extending into the filter element and adapted to pilot over a projection in the center of the inner baflle.

8. In an air cleaner, a generally cylindrical housing having an outside wall, a rear wall closing one end of the outside wall, a rotatably mounted fan rotor in the other end and means for rotating it, the housing having a forward shroud extending forwardly across and around the fan rotor, a centrally disposed inlet in the shroudopening inside of the fan rotor for dirty air, an inner sleeve adjacent the rear of the fan rotor extending a substantial distance rearwardly therefrom and defining an open rearwardly extending annular passage with the outside wall arranged to receive a helical rearwardly moving swirl of dirty air against the inside of the outer wall from the fan rotor, a generally cylindrical annular filter element having an outside diameter less than the inside diameter of the housing and extending forwardly from the rear wall of the housing to filter dirt from the air drawn from the inside of the helical swirl, outlet means of generally annular form in the rear wall disposed adjacent the outer wall of the housing adapted to discharge dirt thrown centrifugally to the outside of the swirl and having an outer diameter substantially that of the outer diameter of the annular air passage, and a clean air outlet in the center of the rear wall in communication with the inside of the cylindrical annular filter element.

9. The structure of claim 8 further characterized in that the forward shroud increases uniformly in cross section rearwardly from the centrally disposed inlet to a point generally opposite the rear of the fan rotor.

References Cited in the file of this patent UNITED STATES PATENTS 1,430,066 Evans Sept. 26, 1922 1,743,344 Hawley Jan. 14, 1930 1,774,062 Juelson Aug. 26, 1930 1,875,427 Donaldson Sept. 6, 1932 2,010,456 Jones Aug. 6, 1935 2,118,167 Connor May 24, 1938 2,192,515 Crane et al Mar. 5, 1940 2,243,637 Landis et a1 May 27, 1941 2,828,831 Boretti et al Apr. 1, 1958 FOREIGN PATENTS 323,078 Great Britain Dec. 24, 1929 886,478 France July 5, 1943 917,117 France Sept. 2, 1946 

